From: Borislav Petkov <bp@alien8.de>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Tony Luck <tony.luck@intel.com>,
Andy Lutomirski <luto@kernel.org>,
Rik van Riel <riel@surriel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Fenghua Yu <fenghua.yu@intel.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v2 8/8] x86/fpu/xstate: Restore supervisor xstates for __fpu__restore_sig()
Date: Fri, 28 Feb 2020 19:31:31 +0100 [thread overview]
Message-ID: <20200228183131.GE25261@zn.tnic> (raw)
In-Reply-To: <9a283ad42da140d73de680b1975da142e62e016e.camel@intel.com>
On Fri, Feb 28, 2020 at 10:11:44AM -0800, Yu-cheng Yu wrote:
> CET has 16 bytes for ring-3 setting, 24 bytes for ring-0.
> Saving supervisor states somewhere else and copying back is not better
> either.
Well, if you're going to save a lot bigger user states area which is
going to be absolutely wasted cycles in that case, you better save those
couple of bytes in another buffer and then copy them into the final state
buffer which gets restored.
> We save supervisor states only when xfeatures_mask_supervisor() is not
> zero.
And on which systems is it not zero? On systems which have supervisor
features or on systems which have *and* *are* *using* supervisor
features?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-02-28 18:31 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 20:18 [PATCH v2 0/8] Support XSAVES supervisor states Yu-cheng Yu
2020-01-21 20:18 ` [PATCH v2 1/8] x86/fpu/xstate: Define new macros for supervisor and user xstates Yu-cheng Yu
2020-02-20 11:47 ` Borislav Petkov
2020-02-20 20:23 ` Yu-cheng Yu
2020-01-21 20:18 ` [PATCH v2 2/8] x86/fpu/xstate: Separate user and supervisor xfeatures mask Yu-cheng Yu
2020-02-21 10:34 ` Borislav Petkov
2020-01-21 20:18 ` [PATCH v2 3/8] x86/fpu/xstate: Introduce XSAVES supervisor states Yu-cheng Yu
2020-01-21 20:18 ` [PATCH v2 4/8] x86/fpu/xstate: Define new functions for clearing fpregs and xstates Yu-cheng Yu
2020-02-21 14:04 ` Borislav Petkov
2020-01-21 20:18 ` [PATCH v2 5/8] x86/fpu/xstate: Rename validate_xstate_header() to validate_xstate_header_from_user() Yu-cheng Yu
2020-02-21 14:13 ` Borislav Petkov
2020-01-21 20:18 ` [PATCH v2 6/8] x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates Yu-cheng Yu
2020-02-21 14:30 ` Borislav Petkov
2020-01-21 20:18 ` [PATCH v2 7/8] x86/fpu/xstate: Update copy_kernel_to_xregs_err() for XSAVES supervisor states Yu-cheng Yu
2020-01-21 20:18 ` [PATCH v2 8/8] x86/fpu/xstate: Restore supervisor xstates for __fpu__restore_sig() Yu-cheng Yu
2020-02-21 17:58 ` Borislav Petkov
2020-02-27 22:52 ` Yu-cheng Yu
2020-02-28 12:17 ` Borislav Petkov
2020-02-28 12:51 ` Sebastian Andrzej Siewior
2020-02-28 15:53 ` Yu-cheng Yu
2020-02-28 16:23 ` Borislav Petkov
2020-02-28 16:20 ` Yu-cheng Yu
2020-02-28 16:50 ` Sebastian Andrzej Siewior
2020-02-28 16:54 ` Yu-cheng Yu
2020-02-28 17:22 ` Borislav Petkov
2020-02-28 18:11 ` Yu-cheng Yu
2020-02-28 18:31 ` Borislav Petkov [this message]
2020-02-28 21:22 ` Yu-cheng Yu
2020-02-28 21:47 ` Borislav Petkov
2020-02-28 22:13 ` Yu-cheng Yu
2020-02-29 14:36 ` Borislav Petkov
2020-03-02 18:09 ` Yu-cheng Yu
2020-03-04 18:18 ` Yu-cheng Yu
2020-03-06 20:50 ` Borislav Petkov
2020-03-10 20:36 ` Yu-cheng Yu
2020-03-10 21:16 ` Thomas Gleixner
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